1. Field of the Invention
The present invention relates to a power unit that includes an engine and a transmission, in which gears are changed using first and second gearshift clutches.
2. Description of Background Art
A power unit is known that includes a transmission having first and second gearshift clutches. The first and second gearshift clutches transmit or disconnect power from an engine to first and second gearshift portions, respectively. These gearshift clutches achieve a change of gears. See, for example, Japanese Patent Laid-Open No. 2002-357267.
In the power unit having the transmission that includes the first and the second gearshift clutches, the transmission may be arranged to have a gearshift shaft disposed in parallel with an output shaft (e.g., a crankshaft) of the engine in order to build a smaller power unit in an axial direction of the engine output shaft. If, at this time, the gearshift clutches are disposed inside a crankcase that rotatably supports the crankshaft, the gearshift shaft that supports the heavy gearshift clutches is reliably supported by the crankcase at a position of sandwiching the gearshift clutches. Contrary to this advantage of the known art, a center distance between the crankshaft and the gearshift shaft becomes greater so that interference can be avoided between the crankshaft and the gearshift clutches having a relatively large diameter. This results in the power unit becoming larger in a direction of arranging the crankshaft and the gearshift shaft.